Ke-Fang Hsu

Use CCT and lighting distribution control algorithm for optimized energy saving with human factor lighting

In this study, a process for optimizing the color temperature and lighting distribution on indoor LED lighting for human factor and energy saving is proposed. Based on the features of LED lighting, the diversified fixture design is more possibilities, such as the fixture with color-temperature and lighting distribution tunable. Therefore, the generalized reduced gradient optimization method is used to calculate the corrected color temperature of the fixture for the seat near the window affected by sun light. This research result could be used in the LED lighting design for more energy saving.

Specific lighting spectrum matching by normalized correlation coefficient and generalized reduced gradient method

The optimization matching procedure for specific LED spectrum matching is proposed by the normalized correlation coefficient and generalized reduced gradient method in this study. The different spectrum means different color temperature, color rendering index, and lighting quality features. However, the specific spectrum for human centric lighting or light therapy may not be achieved by single light source but by multi-lighting sources for cost consideration. Therefore, the Gaussian distributions are used to define the specific spectrum and generate the row data rapidly for the matching calculation. The normalized correlation coefficient is used to evaluate the spectrum matching result and optimized by generalized reduced gradient method. Finally, the specific spectrum is matched with multi-lighting sources in the optimized mixing ratio from the lighting sources database.

Fast mapping algorithm of lighting spectrum and GPS coordinates for a large area

In this study, we propose a fast rebuild technology for evaluating light quality in large areas. Outdoor light quality, which is measured by illuminance uniformity and the color rendering index, is difficult to conform after improvement. We develop an algorithm for a lighting quality mapping system and coordinates using a micro spectrometer and GPS tracker integrated with a quadcopter or unmanned aerial vehicle. After cruising at a constant altitude, lighting quality data is transmitted and immediately mapped to evaluate the light quality in a large area.

Selecting conversion phosphors for white light-emitting diodes package by generalized reduced gradient method in dispensing application

The conversion-phosphor selection engine with chromaticity coordinates and additive color-mixing theory for light-emitting diodes is constructed. The parameters are linked by the generalized reduced gradient method for optimization. Finally, this model can be used in the LED dispensing process for 2700K and high color rendering index requirement.

Stepless tunable four-chip LED lighting control on the black body radiation curve with generalized reduced gradient method

In this paper, the algorithm for the stepless tunable four-chip LED on the black body radiation curve, using the Generalized Reduced Gradient method, is proposed. The lumen outputs of four-chip LED, for color temperatures between 2500K and 6500K, are then calculated in real-time, without using a lookup table, and for high quality lighting design.

The design of asymmetrical TIR optics with micro-structure for museum exhibition lighting

An analysis of asymmetrical lenses with microstructures for museum exhibition lighting is proposed. According to simulation results, using an asymmetrical light shape will increase the illumination uniformity more than 13.1% relative to the standard lambertian light shape.

Design and implement an AC LED light engine with smart phone control

In this paper, a prototype of AC LED light engine is implemented. This light engine is highly designed and integrated with different fields, including optical, mechanical, electrical part, control system, and safety requirement. Our light engine can directly install in different lighting fixtures like down light or spot light, which is very convenient and cost-saving for luminaries manufactures. It also can offer customized solutions about CCT, beam angle, even involved intelligent control system in the future. The specification of light engine is that the CCT is 4601K, CRI is 81, and the lm/W is 102 at 10W input power.

High efficiency batwing thin-film design for LED flat panel lighting

In this study, high efficiency thin film design with low UGR and batwing distribution in LED flat panel lighting is proposed. The batwing distribution can be used to enhance the uniformity for indoor lighting. Therefore, the micro-structure film is designed with v-cut and lenticular to transform the light distribution from lambetrian to batwing and keeps low UGR within 19. In this study, the holes pattern design on the micro-structure film aforementioned to enhance the light efficiency was analyzed and tested. According to the thin-film simulation model, the holes pattern on the batwing distribution film is proposed to enhance the efficiency more than 2 % with only 1% UGR losses. As a result, the micro-structure film is suitable to create an ideal batwing light distributions in office lighting.